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511.
经过2006年以来市场导入和培育,“导航”已经成为有车人士不再陌生的字眼,导航产品也拥有了数百万的用户群。随着用户逐步熟悉这个产品,“导航电子地图升级”成为越来越多用户关注的服务项目。  相似文献   
512.
Past studies have shown that the level of roadway lighting is an important factor for nighttime roadway safety. To evaluate roadway lighting systems and maintain their functionality, it is essential to perform field lighting measurements. Currently, field measurements of roadway lighting systems are often conducted by handheld light meters using a short sample section. The evaluation of an entire corridor or a longer section is difficult when using the traditional manual measurement methods. This paper addresses this difficulty by developing a new lighting measurement system that can be used to collect massive amounts of lighting level data in an efficient, safe, and effective manner. The system consists of a light meter, a distance measurement instrument (DMI), a computer, software, and an electronic converter circuit to connect the computer and other hardware. Software was developed for the communication link between the computer and the light meter, and to record both the distance and illuminance data. The system was calibrated and validated with the field data. The new system will not only reduce future data collection costs, but also improve safety for field data collection personnel. The system has been approved for use to collect illuminance data on Florida state roads greater than or equal to 250-miles in length.  相似文献   
513.
针对铁路运输的货物在途中被盗现象,提出了货车、集装箱防盗系统的设计原理,给出了系统硬件结构示意图和软件设计框图并对其在 T M I S中的使用前景进行了展望。  相似文献   
514.
A new platoon control concept is introduced, called Back Control, in which the controller of a given vehicle utilizes state information from the lead, preceding, and following vehicles, as well as the vehicle itself. Simulations are carried out on two non-steady state platoon operations - vehicle exit and vehicle entry from a platoon. A previously developed longitudinal controller is utilized as a reference to the proposed Back controller and a ride quality index is used to assess passenger comfort in these simulations. It is shown that the Back controller has advantages over the reference controller in these two operations and that it is therefore worth examining as a candidate controller of vehicular platoons, especially in non-nominal operations.  相似文献   
515.
A summary of the seasonal development of the Northeast Water Polynya ice cover characteristics is presented. This is based primarily on satellite remote sensing observations, with some in situ measurements, including both new and published data.  相似文献   
516.
This paper presents a survey of the state-of-the-art in predicting the wheel vibrations in a complex dynamic vehicle suspension system and their influence on the forces transduced in a high frequency area from the tire to the vehicle's body. Secondly it presents also the transient evolution of tire models used for prediction and understanding high frequency movements in the tire's contact area, producing the guiding forces and torques during vehicle handling.  相似文献   
517.
This paper presents vibration control of a passenger vehicle using an electronically controllable electro-rheological (ER) engine mount. A mixed-mode ER engine mount operating under the flow and shear modes is devised and manufactured. After establishing the dynamic model of the proposed ER engine mount, both field-dependent displacement transmissibility and dynamic stiffness of the ER engine mount are empirically evaluated. The ER engine mount is then incorporated with a full-vehicle model in order to investigate vibration control performance at the driver's seat position. The governing equation of motion of the full-vehicle model is formulated by considering engine excitation force, followed by designing a skyhook controller to attenuate unwanted vibration. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at idle speed are evaluated in the frequency and time domains.  相似文献   
518.
The aim of this paper was to investigate the validity of the Efficient Market Hypothesis in conjunction with Rational Expectations in the formation of dry bulk ship prices over the period January 1976-December 1997. Tests for market efficiency include those of orthogonality and unpredictability of excess returns on investments and tests based on the Vector Autoregressive models proposed by Campbell and Shiller. The latter methodology is extended further to a 3-variable Vector Autoregressive model, which is applicable to real assets with limited economic life. Results indicate that prices for newbuilding and second-hand vessels are not determined efficiently in the sense of Fama. Failure of the Efficient Market Hypothesis in the formation of ship prices is explained by the existence of timevarying risk premia, which relate excess returns to investors' perceptions of risk. These are modelled through the Generalized Autoregressive Conditional Heteroscedasticity in mean (GARCH-M) models. The results have important implications for shipping investment strategies, both in the newbuilding and second-hand markets.  相似文献   
519.
The quality of numerical wave forecasts can be improved significantly by assimilating wave observations prior to the forecast. In the present study a technique for such assimilation is developed that exploits (a) the efficiency of a limited number of integral control variables, and (b) the effectiveness of variational (model-consistent) assimilation. The formal procedure is independent of the type of control variables and of the wave model (moreover, no adjoint wave model is required). In the present study, integral control variables are chosen to represent large-scale errors in the driving wind fields and uncertainties in the wave model. The assimilation technique is validated with observations of the ERS-1 satellite altimeter and two waverider buoys in two consecutive storms in the Norwegian Sea. The assimilation of the observations reduced the errors in the forecasted significant wave height at the buoy locations typically from 25% to 12%. For low-frequency waves the effect of the assimilation is similarly significant at one buoy location but marginal at the other buoy location.  相似文献   
520.
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